The AC74 dual positive-edge-triggered devices are D-type flip-flops.
A low level at the preset (PRE)\ or clear (CLR)\ inputs sets or resets the outputs, regardless of the levels of the
other inputs. When PRE\ and CLR\ are inactive (high), data at the data (D) input meeting the setup time
requirements is transferred to the outputs on the positive-going edge of the clock pulse. Clock triggering occurs
at a voltage level and is not related directly to the rise time of the clock pulse. Following the hold-time interval,
data at the D input can be changed without affecting the levels at the outputs.